The classical air conditioning circuit includes a compressor, a condenser, a pressure-reducing device and an evaporator, through which, in that order, a cooling fluid flows. The cooling fluid is compressed in a gaseous state and brought to a high pressure by the compressor. It is subsequently transformed into a liquid state by the condenser, then subjected to a drop in pressure in passing through the pressure-reducing device. The liquid is partially evaporated in the pressure-reducing device while cooling. Upon leaving the pressure-reducing device, the cooling fluid is in the form of a mixture of vapor and liquid at low pressure which is transmitted to the evaporator, where it is transformed into a gaseous state.
In existing constructions, a thermostatic pressure reducer is used to implement the pressure reduction. Such a pressure reducer is intended to input to the evaporator in an optimal manner while maintaining a selected overheat at the evaporator outlet; this enables the flow rate of the cooling fluid circulating in the circuit to be adjusted according to the heat loads.
Nonetheless, connection of such a pressure reducer to other elements of the air conditioning circuit is costly. In fact, such a pressure reducer includes four connecting points, two of said connection points being located on a lateral face for connection to the evaporator inlet and the evaporator outlet via two connection conduits, and the other two connection points being located on the other lateral face for connection to the condenser outlet (or the accumulator outlet) and the condenser inlet via two other connection conduits. Furthermore, at least two fixation clamps are necessary to fix the connection conduits together. The centerline distance of alignment of the two connection conduits located on the same lateral face must be strictly observed, and, in particular, the two connection conduits used to connect the pressure reducer to the evaporator inlet and outlet must have a specific and complex shape in order to enable the connection. This, in turn, increases the overall cost of the pressure reducer.
In other constructions, the pressure-reducing device is a calibrated orifice. Such a pressure-reducing device can easily be connected to the rest of the air conditioning circuit, in view of the simplicity of its structure. Nevertheless, the performance of a calibrated orifice for regulating the flow of cooling fluid as a function of thermal loads is not in line with that of thermostatic pressure reducers. This being the case, an accumulator is used as a complementary device at the evaporator outlet to prevent a too-high flow rate of cooling fluid from reaching the evaporator and to avoid surges of liquid at the compressor. This accumulator corresponds to a storage area for the non-circulating batch of cooling fluid. This storage area can increase or decrease as a function of operating conditions. As a consequence, the accumulator must be particularly voluminous, which increases the overall dimensions of the air conditioning installation.